1. Field of the Invention
This invention relates to an electronic timepiece having functional hands and adapted for detecting information other than time by a sensor and indicating the information by indicating hands.
2. Related Art
A variety of electronic timepieces having the function of indicating the depth of water by a water pressure sensor as an additional function, are is presented to the market. These timepieces are adapted for digitally indicating the depth of water by electro-optical display units. Display parts are hardly visible in water where extraneous light is hard to reach and, in case of a liquid crystal display, display can hardly be read from a certain viewing angle.
On the other hand, water depth indication by an indicating hand according to the Bourdon tube system has such an advantage that the water depth can be read easily from the hand position. In JP patent KOKAI publication No. 61-34416, there is proposed a timepiece provided with an additional function of indicating the water depth by an indicating hand. However, the timepiece disclosed in JP patent KOKAI publication No. 61-34416 is provided with only one indicating hand for indicating the current diving water depth.
Meanwhile, when a diver operating in water is floating up, nitrogen or helium in the blood tends to be supersaturated due to reduction in an external pressure to produce dysbarism in which air bubbles are produced in the blood to injure body organs. The customary process in combatting the symptom is to compare the diving time duration to the maximum depth reached during diving to take suitable measures to prevent dysbarism. It is therefore desired by divers operating in water that the depth of water during diving and the maximum depth reached during diving are displayed.
From this viewpoint, an apparatus for measuring and processing the depth of water by a water pressure sensor and indicating the depth of water by the indicating hand by an electromechanical transducer needs to be provided with a water depth hand which, in synchronism with the divers movement in water, is turned in a forward direction during deep diving for indicating a deep depth of water and in a reverse direction during floating for indicating a shallow depth of water, and with a maximum water depth hand adapted for indicating the maximum depth reached and adapted for being turned only in case of deep diving.
On the other hand, if the water depth indication is made by an indicating hand, an electronic timepiece structure is such that a space occupied by a display mechanism is increased as compared with digital display while, the time for driving the train wheels for display is also increased. The JP patent KOKAI publication No. 59-159083 and the Switzerland patent 568608 disclose a wrist watch having a water depth meter and an indicating hand.
However, in these publications, only the schematics of the timepiece, the sensor mounting position and specifications are explained, where as the inner structure of the timepiece movement is not explained in detail.
Thus the problem of reducing the size and the thickness of the timepiece movement by efficiently arranging the motors and the train wheels and providing a water depth measurement system with good follow-up for displaying the current diving depth, has not yet been overcome.